The Vatican denied an Italian newspaper report on Wednesday that Pope Francis has a benign brain tumor, saying the 78-year-old pontiff was in good health and denouncing the article as "inexcusable".

In one of three increasingly tough denials issued as the story spread around the world, the Vatican called the report in Quotidiano Nazionale daily "a grave act of irresponsibility, absolutely inexcusable and unconscionable".

Francis held his weekly general audience before tens of thousands of people in St. Peter's Square and afterwards returned to a three-week gathering of bishops, which he has been attending daily.

Quotidiano Nazionale reported on its front page on Wednesday that a Japanese doctor and his team had secretly flown from Tuscany to the Vatican on a helicopter bearing the Holy See's white-and-yellow flag to examine the pope "some months ago".

Under the headline "The Pope is Sick", it said the Argentine pontiff was diagnosed with "a small dark spot on the brain", but that it was curable without surgery.

"I am able to confirm that the pope is in good health," chief spokesman Father Federico Lombardi said in a statement he read out during a news conference on another topic.

He said he had checked directly with the pope and other Vatican officials.

"No Japanese doctor has visited the pope in the Vatican and there have been no examinations of the type indicated in the article," he said, dismissing the story about the helicopter.

Quotidiano Nazionale named the Japanese doctor as Takanori Fukushima, who usually works in the United States. He could not be immediately reached for comment early on Wednesday.

Lori Radcliffe, practice administrator for Fukushima at the Carolina Neuroscience Institute in Raleigh, North Carolina, described the report as "absolutely false".

She told Reuters Fukushima saw the pope and shook his hand alongside thousands of people this year at a general audience at the Vatican but had never treated or evaluated him.

This year, Francis has made trips to Asia, Bosnia-Herzegovina, Latin America, the United States and in Italy.

In a television interview last March on the second anniversary of his election, Francis said he believed his pontificate would be short and he would be ready to resign like his predecessor Pope Benedict rather than lead the church for life..

The pope has appeared in good health in recent months apart from some leg pain due to sciatica, for which he undergoes regular therapy. He lost part of one lung to disease as a young man.